Vulnerability · Published Jun 24, 2025 · Assigned by mozilla
CVE-2025-6427connect-src Content Security Policy restriction could be bypassed
Critical 9.1
In plain English
A critical-severity security flaw in Firefox from Mozilla. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 31% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)9.1Critical
Exploit odds (30 days)0.4%top 69.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
An attacker was able to bypass the `connect-src` directive of a Content Security Policy by manipulating subdocuments. This would have also hidden the connections from the Network tab in Devtools. This vulnerability was fixed in Firefox 140 and Thunderbird 140.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu:22.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2025-6427 |
| Ubuntu:24.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2025-6427 |
| Ubuntu:24.04:LTS | mozjs115 | no fix listed | UBUNTU-CVE-2025-6427 |
| Ubuntu:22.04:LTS | mozjs78 | no fix listed | UBUNTU-CVE-2025-6427 |
| Ubuntu:22.04:LTS | mozjs91 | no fix listed | UBUNTU-CVE-2025-6427 |
| Ubuntu:22.04:LTS | thunderbird | 1:140.7.1+build1-0ubuntu0.22.04.1 | UBUNTU-CVE-2025-6427 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | see references |
| Mozilla | Thunderbird | see references |
Weakness: CWE-693 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N